So called “solid ink” printers offer many advantages over many other types of high speed or high output document reproduction technologies such as laser and inkjet approaches. These often include higher document throughput (i.e., the number document reproduced over a unit of time), fewer mechanical components needed in the actual image transfer process, fewer consumables to replace, sharper images, as well as being more environmentally friendly.
A schematic diagram for a typical solid ink printing device is illustrated in FIG. 1. The solid ink printer 100 has a solid ink reservoir 110 which receives solid ink blocks or pellets which remain in solid form at room temperatures. The ink stock can be refilled by a user by simply adding more as needed to the reservoir 110. Separate reservoirs, or at least separate reservoir components, are used for color printing. For, example, only black solid stock is needed for monochrome printing, while solid ink stock of black, cyan, yellow and magenta are typically needed for color printing.
An ink heater 120 melts the ink by raising the temperature of the ink sufficiently above its “freezing point.” The liquefied ink is supplied to a group of print heads 130 by gravity, pump action, or both. In accordance with the image to be reproduced, and under the control of a printer controller 180, a rotating print drum 140 receives ink dots representing the image pixels to be transferred to printing stock 170 from a sheet feeder 160. To facilitate the image transfer process, a pressure roller 150 presses the printing stock 170 against the print drum 140, whereby the ink is transferred from the print drum to the printing stock. The temperature of the ink can be carefully regulated so that the ink solidifies just after the image transfer.
Printer operation thermal set points additionally influence image transfer quality and durability, and are related to the ink properties and ink thermal behavior. As an example, the drum is held at a predetermined temperature range to allow just the right ink drop spread and transfer to media, and the pre-heater warms media prior to image transfer so the ink properly adheres. When these parameters are programmed into the printer without a means to couple them to a specific ink formulation, composition of ink used over the product life is highly constrained. Flexibility in post product release ink formulation change is minimal or non existent. This inflexibility in permitting ink evolution for an existing printer product is a limitation of the prior art for solid ink storage and delivery systems.
While there may be advantages to the use of solid ink printers compared to other image reproduction technologies, printer architecture, high speed and voluminous printing sometimes creates problems not satisfactorily solved by the prior art solid ink printing approaches. To meet the large ink volume requirement, the ink reservoirs are typically either able to be replenished by loading pellets or ink chunks to the reservoir throughout operation of the printer, or multiple ink reservoirs supplying the same color are linked so that when one container is exhausted, the printer automatically switches to another supplied reservoir of the same color.
Replenishing ink by the customer can lead to loading the wrong ink color or the wrong ink formulation for the particular reservoir. In response, prior art solid ink printers often employ a complicated system of ink shape or container interlocks to discourage improper ink pellet/chunk placement. There are also problems associated with insuring that the ink properly dispenses out of the reservoir, sensing the level of ink present in the reservoir, and others owing to the cost and complexity of such features. In summary, solid ink in pellet form provides many advantages and may be easier to refill, but pose a greater risk of loading the wrong ink. Large ink blocks with special shapes (that are matched by the correct reservoir or reservoir compartment) may reduce ink color mistakes but might carry more cracks and structural flaws and would be very vulnerable to handling damage, making them difficult to handle and load at times.
In addition, some forms of ink containers for solid ink printers may not encourage recycling due to the tendency of consumers to treat them as disposable items used only for packaging for transport and storage of ink.
There is also a desire on the part of consumable suppliers to efficiently obtain information related to the printer activity so that the customer can be better served in the future.